Season 4

The fourth and final season of Lincoln Heights premiered on Monday September 14, 2009 with 10 new episodes. The season starts with Charles and Cassie being charged for the murder of Charles' stepfather. There was not enough evidence, so the case was closed. But immediately afterward, the police check both Charles' and Cassie's homes for the stolen money that Charles has, but the money is safely stashed. Lizzie finds trouble when she is encouraged to join a community club. She starts rumors about a schoolmate and then apologizes and quits the club. Meanwhile, Charles discovers he received a letter from his father fifteen years ago, which his mother kept from him.

After obtaining his father's phone number, the two talk and decide to meet. Charles asks Cassie to go with him, but her parents forbid her. She ignores them and instead sneaks out to join Charles and the spend the night with him. Cassie leaves the following morning to face her angry parents, but Charles decides to stay in order to get to know his family. Lizzie makes friends with a Mexican boy while at a community recreation center. He gets very attached to Lizzie and agrees to let Lizzie take his special bear home to fix after another boy, who picks on him, tears it. While walking home alone, Lizzie gets attacked by a man who is after the teddy bear because of the drugs concealed in it.

Cassie finds out that Charles has kept yet another secret from her, which causes him to lose Cassie's trust. To cope with the pain, she decides to go to a popular club with Sage, Sage's boyfriend and Serge, who likes Cassie. While at the club, Cassie goes to the bathroom only to find Serge waiting for her. He tries to touch her, but she kicks him in the crotch. Meanwhile, Lizzie leaves the Outreach dance early after Andrew tries to kiss her during a song which brings back memories of Johnny. The next day, she seeks Andrew out to apologize for leaving early and to explain why. They end up sharing a kiss. The next episode starts out with a surprise visit from Grandpa, who develops a serious crush on the female pastor. He is devastated when he finds out she is engaged to former pastor, Deacon Jones.

Lizzie invites Andrew to meet her family, including her grandfather, who does not appear to be pleased with her new boyfriend. Later on, Cassie and Charles's relationship could be getting weaker. Charles's brother, Travis, visits where they get into serious trouble. Lizzie furthers her deep relationship with Andrew by including him in family activities. During a game called "Name That Bible Verse", things start to get a little out of hand. Deacon Jones accuses Lizzie of cheating and Grandpa embarrasses Lizzie by reacting aggressively. However, Eddie manages to calm things down before they get violent.

The next day, Lizzie and Andrew are having a private moment on the staircase when Grandpa's crush appears at the door. He apologizes for "flying off the handle" the previous night. She explains that she and Deacon Jones broke up because she feels like she was with the wrong man. Grandpa and the pastor share a passionate kiss, watched by Andrew and Lizzie. Tay meets his idol, Trey Songz, and gets to sing along on stage with him. At the very end of the episode, Jen is rushed to the hospital at the cause of a sudden illness. While Jen is in the hospital trying to recover, Cassie tries to decide where the future will lead her and Charles. It is revealed later, as Jen is making a full recovery, that the virus came from the site of the torn down crack house, and not from the clinic as was feared, so the clinic stays open.

Towards the end of the season, Charles decides to join the Army and Cassie considers attending Pratt, a prestigious fine arts/design school in New York City. However, before making their decisions, Cassie and Charles decide to get married and the Sutton and Antoni families race to the ceremony. Just before the ceremony at the courthouse, the mystery of the $100,000 gets solved. It turns out the money was a payoff of an old murder due to a racist prank committed by Eddie's chief when he was a child. A former inmate on parole, Sid Glass, claims the money and gives half to the Sutton family because of their generous help and effort to support her.

Tay writes a hit song dedicated to Nate Ray called "Fight for You." Nate Ray later sees Tay performing his song on a television news story and tells Jen that he sent the song to his army buddies and it went viral. In the end, Cassie and Charles don't end up getting married, but have an engagement party where their loved ones offer them blessings for a potential wedding in the future. Cassie's father attends with Charles' parents. Charles decides against going into the army and instead accepts his father's offer to pay for him to attend a good college.